Walzenmühle

Abstract

Roller mill for comminuting brittle material, with two counter-rotating grinding rollers (1, 2), each having a base body (3) with a circumferential surface (4), wherein a wear-resistant layer (5) with a plurality of profile bodies (6) is provided on the circumferential surface, wherein each profile body (6) is held with a part in at least one bore (7) in the base body (3) and projects with another part from the base body (3), wherein the profile bodies (6) are arranged such that adjacent profile bodies (6) are so closely adjacent to each other that at least 80% of the circumferential surface (4) of the base body (3) is covered by the profile bodies (6), wherein the part of the profile body (6) located in the bore (7) of the base body (3) is designed as a pin (6a) and the part projecting from the base body is formed by a projecting head (6b), and wherein the head (6b) has a bearing surface (6c),with which it rests on the circumferential surface (4) of the base body (3).

Description

[0001] The invention relates to a roller mill for crushing brittle material.

[0002] Roller mills of this type are used, for example, in the cement and minerals industries for crushing limestone, dolomite, or ore. The roller surfaces are subject to enormous wear, necessitating regular reconditioning of the grinding rollers. Various wear protection concepts have been developed to increase the service life of the grinding rollers. In DE 10 2007 032 261 A1, the outer shell is formed by a multitude of segments inserted into longitudinal grooves in the base body. However, this design resulted in flexing movements of the segments on the base body, leading to premature failure.

[0003] EP 0 659 108 B1 proposes a wear-resistant coating applied across the entire surface of the base body. This coating features flat zones made of a highly wear-resistant material, with the spaces between these zones filled with a material of different wear resistance. However, this solution has the disadvantage of being relatively complex to apply and requiring significant effort for repairs, as the entire coating usually needs to be replaced. More recently, a wear-resistant technology has proven effective in which numerous pin-shaped profile elements protrude from the circumferential surface of a base body. The spacing between these elements is chosen such that an autogenous wear-resistant layer of compressed material forms between them during operation. Such a surface coating is described, for example, in EP 0 830 897 B1.This wear protection concept has the advantage that individual, worn profile bodies can also be replaced.

[0004] From EP 1 502 650 A1, a grinding roll is known comprising a roll body and a plurality of wear-resistant elements made of hard metal. Circumferential recesses are provided in the area of ​​the roll ends, with several wear-resistant elements arranged one behind the other in the circumferential direction within each recess. In a central area of ​​the grinding roll, upwardly projecting profile bodies are arranged, preferably spaced apart such that an autogenous wear-resistant layer forms in the spaces between them during the grinding process.

[0005] Another surface armor for rollers of a high-pressure roller press is known from DE 196 38 237 A1, which is formed by a multitude of mushroom-shaped studded bolts protruding from the roller body, which form pockets between them for receiving compressed, fine-grained material.

[0006] This wear protection solution for high-pressure roller presses specifically addresses abrasive wear resulting from relative movement between the material being ground and the grinding roller. In addition to abrasive wear, other damage mechanisms occur on rollers during high-pressure grinding in roller presses. The process-related compressive stress, particularly on the exposed, hard profile sections, leads to a corresponding force being transmitted into the roller base, resulting in permanent damage to the base through cracking and, if the crack propagates, fracture. Furthermore, surface erosion of the base occurs due to the dynamic stress on the autogenous wear protection layer. Additionally, edge fractures frequently occur on the profile sections, especially as a result of stress from larger individual particles. Lateral forces can damage individual profile sections or tear them from their anchoring.

[0007] Modern grinding rollers typically undergo extensive repairs at the end of their service life. This reconditioning essentially involves removing remaining wear elements, machining the damaged surface of the base body, welding on the roller body layer worn away by wear and reworking, and applying new wear elements.

[0008] The invention is based on the objective of providing a wear-resistant coating for a roller mill that avoids or minimizes abrasive wear and mechanical overload of the base body. Ideally, the wear protection should be designed in such a way that reconditioning of the base body is no longer necessary when the grinding roller is reconditioned.

[0009] According to the invention, this problem is solved by the features of claim 1.

[0010] The roller mill according to the invention for crushing brittle material has two counter-rotating grinding rollers, each of which has a base body with a wear-resistant layer formed on its circumferential surface by a plurality of profile elements, wherein each profile element is held in at least one bore in the base body by a portion and projects out of the base body by another portion. The profile elements are arranged such that adjacent profile elements are so closely adjacent to one another that at least 80%, preferably at least 85%, most preferably at least 90% of the circumferential surface of the base body is covered by the profile elements.

[0011] Essentially, the aim is to achieve full-surface protection, with the uncovered areas being formed by the narrow gaps between the profile elements. Ideally, full-surface protection ensures that the roller body suffers no damage whatsoever and therefore does not require reworking when the wear-resistant layer is reapplied. The close surface coverage with the profile elements according to the invention, and the resulting increase in the contact area, prevents overloading and destruction of the profile elements, particularly by larger individual particles in the ground material.

[0012] The full-surface protection of the base body proposed according to the invention prevents significant damage to the base body and the resulting costly repairs. Ideally, only worn or damaged profile elements need to be replaced at specified intervals.

[0013] Further embodiments of the invention are the subject of the dependent claims.

[0014] According to a further embodiment of the invention, the part of the profile body located in the bore of the base body is designed as a pin, and the part protruding from the base body is formed by a projecting head. The head has a bearing surface with which it rests against the circumferential surface of the base body. This design creates a functional separation compared to conventional, pin-shaped profile bodies, with the pins performing the "holding function" and the projecting heads providing "support." Due to the bearing surface of the head being in contact with the base body, the forces acting during grinding are distributed over a significantly larger area, thus considerably reducing the stress on the base body. This can prevent the formation of any cracks.

[0015] To ensure flush contact of the head with the circumferential surface of the base body, the contact surface of the head can be adapted to the curvature of the circumferential surface of the base body, or the contact surface of the head can be flat and the circumferential surface of the base body can have a polygonal profile for flush contact of the head.

[0016] The profile bodies are advantageously dimensioned such that a plurality of profile bodies abut each other in the longitudinal and circumferential directions of the grinding roller. The resulting gaps are preferably only 1 to 8 mm wide and can be filled with a metallic material, preferably white metal, or a non-metallic material, preferably epoxy resin, or with compressed material. To achieve the most complete coverage possible, the heads of the profile bodies have a square, rectangular, or polygonal shape when viewed from above. The edge length of the heads is preferably 25 to 75 mm, and the thickness of the heads can be 10 to 100 mm, depending on the wear characteristics to be addressed. The profile bodies are attached to the bores of the base body, for example, by clamping, gluing, soldering, or a combination of these methods.

[0017] In principle, the profile bodies can be made of a single material. However, a sandwich construction is also possible, in which the part located in the bore is made of a softer material, such as steel, and the part protruding from the base body consists at least predominantly of a harder material, such as cemented carbide. With the previous pin-shaped profile bodies, this sandwich construction was hardly feasible, as the grinding rollers could only be reconditioned when parts of the roller surface were worn down to the base body. In contrast, the new wear protection concept allows reconditioning before the base body is damaged, without reducing service life.

[0018] According to a preferred embodiment of the invention, the profile bodies are designed such that areas with an autogenous wear-resistant layer are also formed. In one exemplary embodiment, this is achieved by the heads of the profile bodies having at least one recess on their side facing away from the pin for receiving compressed material. According to another embodiment of the invention, the heads of the profile bodies are designed such that pockets for receiving compressed material are formed between adjacent heads. For this purpose, the heads can, for example, be rounded or pyramid-shaped on their side facing away from the pin.According to a third variant, it is provided that adjacent profile bodies protrude from the circumferential surface of the base body to different extents, so that a profile body that protrudes less far is surrounded by profile bodies that protrude further, so that the resulting depression is filled with compressed material during operation.

[0019] Further advantages and embodiments of the invention are explained in more detail below with reference to the description and the drawing.

[0020] The drawing shows Fig. 1 a schematic side view of a roller mill, Fig. 2 a top view of the surface of the grinding roller according to a first embodiment, Fig. 3 a top view of the surface of the grinding roller according to a second embodiment, Fig. 4 a side view of a profile body according to a first embodiment, Fig. 5 a side view of a profile body according to a second embodiment, Fig. 6 a cutaway partial view of the profile elements resting on the base body according to a first embodiment, Fig. 7 a cutaway partial view of the profile elements resting on the base body according to a second embodiment, Fig. 8 and Fig. 9 three-dimensional representations of various profile elements, Fig. 10-13 side views of various profile bodies, Fig. 14 Side view of a profile body with recess, Fig. 15 Three-dimensional representation of the profile body according to Fig. 14, Fig. 16 sectioned partial views of different variants of filling the joints between adjacent profile bodies, Fig. 17 - 19 different designs of profile bodies arranged side by side, Fig. 20 - 27 different embodiments of profile bodies composed of pins and heads.

[0021] The in Fig. The roller mill or roller press shown in Figure 1 consists of two counter-rotating grinding rollers 1, 2, each having a base body 3 with a circumferential surface 4, wherein a wear-resistant layer 5 with a plurality of profiled elements 6 is provided on the circumferential surface. The roller mill can be used, in particular, in the cement and minerals industries for the comminution of brittle materials such as limestone, dolomite, or ore. The rollers typically have a diameter of up to 2.4 m and more and are operated in the bed-compression range. From the top views of grinding rollers according to the Fig. 2 and Fig. Figure 3 shows that the profile bodies are primarily square, although rectangular or polygonal shapes are also conceivable. The individual profile bodies are arranged in several rows and are closely adjacent to one another, leaving only narrow joints of 1 to 8 mm. The profile bodies can be installed in a cross-joint pattern according to... Fig. 2 or in a staggered formation according to Fig. 3 will be arranged.

[0022] The in Fig. 4. The profile body 6.2, shown in more detail, essentially consists of a pin 6.2a which fits into a bore 7 of the base body 3 ( Fig. 2 or Fig. 3) is inserted and a part protruding from the base body, which is formed by a projecting head 6.2b. In the Fig. 2 and Fig. Figure 3 shows the bores 7 as dashed lines, with the hole spacing corresponding to the previous hole spacing for pin-shaped profile bodies. Due to the preferred dimensions of the profile bodies according to the invention, it is sufficient to use every second bore. With a new base body, of course, only the actually necessary number of bores will be provided. If the profile bodies according to the invention are even larger, they can also be designed with two or three pins whose spacing matches that of the bores 7. This also results in the anti-rotational stability that would otherwise be achieved by the connection.

[0023] The edge length l of the heads 6.2b is preferably between 25 and 75 mm, with an edge length l of 50 mm + / - 10 mm proving particularly advantageous. The thickness d of the heads 6.2b is expediently adapted to the expected wear during grinding operation, but can in particular be between 10 and 100 mm. Fig. Figure 5 shows a profile body 6.1 with a head 6.1b and a tenon 6.1a, wherein the head 6.1b is opposite the head 6.2b of the Fig. 4 has a significantly greater thickness.

[0024] The head 6b of the profile body 6 also has a bearing surface 6c with which it rests on the circumferential surface 4 of the base body 3. There are two variants for this, which are described in the Fig. 6 and Fig. 7 are shown. When executed according to Fig. 6 The base body 3 has a polygonal profile on its outer surface which is adapted to the edge lengths of the profile bodies 6, so that the flat bearing surfaces 6c of the profile bodies 6 rest on correspondingly flat partial areas of the circumferential surface 4 of the base body 3. In the embodiment according to Fig. In the 7-part design, the circumferential surface 4.1 of the base body 3.1 is cylindrical. For flush seating of the head 6.2 on the circumferential surface 4.1, the bearing surfaces 6.2c are adapted to the curvature of the circumferential surface 4.1 of the base body 3.1. In both embodiments, the heads of the profile bodies thus rest flush with their bearing surfaces on the circumferential surface of the base body, so that the forces occurring during the grinding process are transferred to the base body over a large area.

[0025] In the Fig. Figures 8 to 15 show different profile body shapes. In principle, it is possible to form the profile body, consisting of pin 6a and head 6b, in one piece ( Fig. 8) Since the head is particularly exposed to abrasive wear, it can also be constructed using a sandwich design ( Fig. 9) The pin 6.3a located in the bore 7 is made of a softer material, and the head 6.3b protruding from the base body is made at least mostly of a harder material. In the illustrated embodiment, the lower part of the head 6.3b is also formed by the softer material of the pin 6.3a.

[0026] In the sectional views of the Fig. Figures 10 to 13 show different head shape variations. A flat head according to Fig. 10 results in a smooth roller. Fig. 11 and Fig. Figure 12 shows two variants with a more or less curved head, while in Fig. Figure 13 shows a pyramid-like head shape. According to a preferred embodiment of the invention, the adjacent profile bodies are intended to ensure full-surface protection of the base body. Nevertheless, the profile bodies are designed to form a surface structure for receiving compressed material. This self-inducing wear protection improves, on the one hand, the coefficient of friction between the material being ground and the grinding roller, and thus the feeding behavior, and on the other hand, further increases the service life of the grinding roller. For this purpose, the profile bodies according to the figures shown are suitable, for example. Fig. 11, Fig. 12 and especially 13. The one in the Fig. 14 and Fig. The profile body 6.4 shown in section 15 enables autogenous profile protection by means of a recess 6.4d provided in the head 6.4b. Alternatively, this profile body is also held in a bore 7 of the base body 3 by a pin 6.4a. During operation, the recess 6.4d will fill with compressed material, thereby significantly reducing wear on the profile body.

[0027] The aim is for the profile bodies 6 to cover the circumferential surface 4 of the base body 3 as completely as possible. Any remaining gaps 10 between the profile bodies ( Fig. 16) should therefore be kept as small as possible. It is intended that the joints 10 be filled with a jointing material 8, which is formed, for example, from a metallic or non-metallic material or compressed material.

[0028] The one in the right half of the Fig. The profile bodies 6.5, 6.6, and 6.7 shown in Figure 16 also have a smooth surface. However, profile bodies 6.5 and 6.7 protrude further from the circumferential surface 4 of the base body 3 than profile body 6.6. If the profile bodies adjoining profile body 6.6 perpendicular to the plane of the drawing are also formed with a raised profile, a depression bounded by the adjacent profile bodies is created in the area of ​​profile body 6.6. As shown, this depression fills with compressed material during operation, thereby forming an autogenous wear-resistant layer 9.

[0029] The principle for forming an autogenous wear protection layer, last described using profile bodies 6.5, 6.6, and 6.7, will be explained below using the following: Fig. Further examples are shown in Figures 17 to 19. Fig. Profile bodies 6.8, which have a pyramid-shaped recess 6.9d, are arranged around a profile body 6.9 with a pyramid-shaped head 6.8b. Here too, an autogenous wear-resistant layer 9 forms between the bounding profile bodies 6.8. In the exemplary embodiment according to Fig. 18. The outer profile bodies 6.10 have a rounded head 6.10b, and the enclosed profile body 6.11 has a correspondingly complementary, rounded recess 6.11d. Here again, an autogenous wear-resistant layer 9 forms between the outer profile bodies 6.10, covering the enclosed profile body 6.11. The resulting surface is relatively smooth and is characterized by the convex, protruding heads 6.10b. In the embodiment according to Fig. 17 The tips of the pyramid-shaped heads 6.8b protrude from the wear-resistant layer 9 and may offer better feed-in behavior of the material to be crushed for certain applications.

[0030] In Fig. Figure 19 shows a variant in which the outer, higher profile bodies 6.11, 6.12 have different thicknesses. Here too, a lower profile body 6.13 is provided in the middle, so that an autogenous wear-resistant layer 9 forms in the space between them. However, in this case, the profile body 6.12 will protrude significantly from the surface of the grinding roller, which can offer particular advantages during feed.

[0031] When manufacturing the profile bodies, it is also advantageous to produce the pin and the head separately and then join the two parts together. This offers additional possibilities, in particular, to promote the formation of an autogenous wear-resistant layer.

[0032] In the exemplary embodiments according to Fig. 20 to 25, the respective head 6.12b to 6.17b is provided with a conical bore 6.14e, ... and the pin 6.12a to 6.17a is also conical, at least in the connection area with the head. According to Fig. 20 The pin 6.12a is flush with the head 6.12b on the upper side. In the embodiment according to Fig. 21 The pin 6.13a protrudes slightly beyond the head 6.13b, so that an autogenous wear-resistant layer can again form between the pins of adjacent profile bodies. In the embodiment according to Fig. 22. The pin 6.14a does not completely fill the bore 6.14e, leaving a recess 6.14d for receiving compressed material. The profile bodies 6.15 to 6.17 of the Fig. Items 23 to 25 are similarly designed. However, the corresponding pins 6.15a, 6.16a and 6.17a are cylindrical with the part to be inserted into the bores 7 of the base bodies 3, while only the connection area with the heads 6.15b, 6.16b, 6.17b is again conical.

[0033] The in the Fig. The 20 to 25 illustrated variants of the pins are preferably glued into the bores 7 of the base body 3. The one in Fig. The profile body 6.18 shown in Figure 26 has a head 6.18b which is connected to a pin 6.18a, designed as a clamping pin and arranged in a through-hole of the head. This pin allows the profile body 6.18 to be clamped in the bore of the base body 8. Alternatively, the pin 6.18a can also be fastened in a blind bore of the head 6.19b of the profile body 6.19, as shown in Figure 26. Fig. 27 shown.

[0034] The close surface contact area of ​​the profile bodies on the circumferential surface of the base body results in a significantly increased contact area compared to conventional pin-shaped profile bodies. This prevents overloading and damage to the profile bodies and the base body, especially from larger individual particles in the material being ground. If a suitable shape of the profile bodies also creates an autogenous wear-resistant layer, this can improve the coefficient of friction between the material being ground and the grinding roller, thus enhancing the feed-in behavior. Furthermore, the autogenous wear-resistant layer protects the covered areas and prevents surface abrasion.

Claims

[1] Roller mill for crushing brittle material, with two counter-rotating grinding rollers (1, 2), each having a base body (3) with a circumferential surface (4), wherein a wear-resistant layer (5) with a plurality of profile bodies (6) is provided on the circumferential surface, wherein each profile body (6) is held with a part in at least one bore (7) in the base body (3) and projects with another part from the base body (3), wherein the profile bodies (6) are arranged such that adjacent profile bodies (6) are so close together that at least 80% of the circumferential surface (4) of the base body (3) is covered by the profile bodies (6), wherein the part of the profile body (6) located in the bore (7) of the base body (3) is designed as a pin (6a) and the part projecting from the base body is formed by a projecting head (6b), and wherein the head (6b) has a bearing surface (6c),with which it rests on the circumferential surface (4) of the base body (3). [2] Roller mill according to claim 1, characterized by , that for flush support of the head (6.2b) on the circumferential surface (4) of the base body (3) the support surface (6.2c) is adapted to the curvature of the circumferential surface (4) of the base body (3) or the support surface (6c) of the head (6b) is flat and the circumferential surface (4) of the base body (3) has a polygonal profile for flush support of the head. [3] Roller mill according to claim 1, characterized by , that the heads (6.4b) of the profile bodies (6.4) have at least one recess (6.4d) on their side facing away from the pin (6.4a) for receiving compressed material. [4] Roller mill according to claim 1, characterized by , that the heads (6b) of the profile bodies (6) are designed such that pockets for receiving compressed material are formed between adjacent heads. [5] Roller mill according to claim 1, characterized by , that the heads of the profile bodies (6 , 6.1 - 6.13) are designed to form a surface structure for receiving compressed material. [6] Roller mill according to claim 1, characterized by , that the heads (6.8b) of the profile bodies (6.8) are rounded or pyramidal on their side facing away from the tenon (6.8a). [7] Roller mill according to claim 1, characterized by , that the heads (6b) of the profile bodies (6) have a square, rectangular or polygonal shape in plan view. [8] Roller mill according to claim 7, characterized by , that the edge lengths of the heads (6) are between 25 and 75mm and the thickness (d) of the heads (6) is 10 to 100 mm. [9] Roller mill according to claim 1, characterized by , that the profile body (6.12 - 6.19) consists of two interconnected parts, with the pin being held in a recess of the head. [10] Roller mill according to claim 9, characterized by, that the cone (6.13a , 6.16a) protrudes on both sides of the head (6.13b , 6.16b). [11] Roller mill according to claim 1, characterized by , that joints of 1 to 8 mm are formed between adjacent profile bodies (6). [12] Roller mill according to claim 1, characterized by , that the profile bodies (6) are held in the bores by bonding, soldering or welding and / or by clamping. [13] Roller mill according to claim 1, characterized by , that the profile bodies (6.3) are constructed in a sandwich design, wherein the part located in the bore is made of a softer material and the part protruding from the base body (3) is made at least mostly of a harder material. [14] Roller mill according to claim 1, characterized by , that the joints existing between adjacent profile bodies (6) are filled with a metallic material or a non-metallic material or compressed material. [15] Roller mill according to claim 1, characterized by , that adjacent profile bodies (6.5 - 6.12) protrude to different distances from the circumferential surface (4) of the base body (3), so that a less protruding profile body is surrounded by more protruding profile bodies, so that the resulting pocket or depression is filled with compressed material during operation. [16] Method for manufacturing the roller mill for comminuting brittle material according to claim 1, comprising Producing a large number of profile bodies (6) by separately manufacturing tenons (6a) and heads (6b) and joining a tenon (6a) and a head (6b), and Providing two counter-rotating grinding rollers (1, 2), each having a base body (3) with a circumferential surface (4), wherein a wear-resistant layer (5) with a plurality of profile bodies (6) is provided on the circumferential surface, wherein each profile body (6) is held with a part in at least one bore (7) in the base body (3) and projects with another part from the base body (3), wherein the profile bodies (6) are arranged such that adjacent profile bodies (6) are so closely adjacent to each other that at least 80% of the circumferential surface (4) of the base body (3) is covered by the profile bodies (6), wherein the part of the profile body (6) located in the bore (7) of the base body (3) is formed as a pin (6a) and the part projecting from the base body is formed by a projecting head (6b), wherein the head (6b) has a bearing surface (6c) with which it rests on the circumferential surface (4) of the base body (3) supports.

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